JP4134925B2 - Manufacturing method of glass substrate for information recording medium - Google Patents

Manufacturing method of glass substrate for information recording medium Download PDF

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JP4134925B2
JP4134925B2 JP2004080069A JP2004080069A JP4134925B2 JP 4134925 B2 JP4134925 B2 JP 4134925B2 JP 2004080069 A JP2004080069 A JP 2004080069A JP 2004080069 A JP2004080069 A JP 2004080069A JP 4134925 B2 JP4134925 B2 JP 4134925B2
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glass substrate
manufacturing
glass
end surface
peripheral end
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JP2005267769A (en
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登史晴 森
要介 山口
慎治 坂井
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Konica Minolta Opto Inc
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Description

本発明は内周端面および外周端面の少なくとも一方を面取り形状とした情報記録媒体用ガラス基板（以下、単に「ガラス基板」と記すことがある）の製造方法に関するものである。   The present invention relates to a method for manufacturing a glass substrate for an information recording medium (hereinafter, simply referred to as “glass substrate”) in which at least one of an inner peripheral end surface and an outer peripheral end surface is chamfered.

大量の情報を高速に書き込み及び読み出しできる情報記録媒体として、いわゆるハードディスクが用いられている。このハードディスクの基板として、平滑性や硬度などに優れるガラス基板が従来のアルミニウム基板に代わって近年広く使用されるようになってきている。このようなガラス基板の従来の製造工程を図５に示す（例えば特許文献１）。   A so-called hard disk is used as an information recording medium capable of writing and reading a large amount of information at high speed. As a substrate for this hard disk, a glass substrate excellent in smoothness and hardness has been widely used in recent years in place of a conventional aluminum substrate. A conventional manufacturing process of such a glass substrate is shown in FIG. 5 (for example, Patent Document 1).

まず、ガラス素材を溶融し（ガラス溶融工程）、溶融ガラスを下型に流し込み、上型によってプレス成形する（プレス成形工程）。プレス成形工程においては一般に、図６に示すような方法が採用されている。同図（ａ）〜（ｃ）に示すように、平面形状を有する成形面を備えた上型１１および下型１２によって、溶融ガラス３を所定厚みにプレス成形する。ここで、ガラス基板の外径を規制するためのリング状外径規制枠を上型・下型間に介設し、成形されるガラス基板前駆体１３の外径を規制してもよい。   First, a glass material is melted (glass melting step), the molten glass is poured into a lower mold, and press-molded with an upper mold (press molding process). In the press molding process, a method as shown in FIG. 6 is generally adopted. As shown in FIGS. 3A to 3C, the molten glass 3 is press-molded to a predetermined thickness by an upper mold 11 and a lower mold 12 having a molding surface having a planar shape. Here, a ring-shaped outer diameter regulating frame for regulating the outer diameter of the glass substrate may be interposed between the upper mold and the lower mold to regulate the outer diameter of the glass substrate precursor 13 to be molded.

そしてプレス成形されたガラス基板前駆体１３は結晶化またはアニ−ルされ、冷却される（結晶化工程またはアニール工程）。冷却されたガラス基板前駆体１３は、必要によりコアドリル等で中心部に孔が開けられる（コアリング工程）。そして、第１ラッピング工程において、ガラス基板の両表面が研削加工され、ガラス基板の全体形状、すなわちガラス基板の平行度、平坦度および厚みが予備調整される。次に、ガラス基板の外周端面および内周端面が研削され面取りされて、ガラス基板の外径寸法および真円度、孔の内径寸法、並びにガラス基板と孔との同心度が微調整された後（内・外径精密加工工程）、ガラス基板の外周端面および内周端面が研磨されて微細なキズ等が除去される（端面研磨加工工程）。次に、ガラス基板の両表面が再び研削加工されて、ガラス基板の平行度、平坦度および厚みが微調整される（第２ラッピング工程）。そしてガラス基板の両表面が研磨加工され、表面の凹凸が均一にされる（ポリッシング工程）。ガラス基板の両表面は必要により粒度の異なる研磨材を用いてさらに研磨加工される（第２ポリッシング工程）。そして最後に、ガラス基板は洗浄および検査され、ハードディスク用のガラス基板として出荷される。
特開２００３−６３８３１号公報（（０００２）〜（０００４）段、図６） The press-molded glass substrate precursor 13 is crystallized or annealed and cooled (crystallization process or annealing process). As for the cooled glass substrate precursor 13, a hole is opened in a center part with a core drill etc. as needed (coring process). In the first lapping step, both surfaces of the glass substrate are ground and the overall shape of the glass substrate, that is, the parallelism, flatness and thickness of the glass substrate are preliminarily adjusted. Next, after the outer peripheral end surface and inner peripheral end surface of the glass substrate are ground and chamfered, the outer diameter and roundness of the glass substrate, the inner diameter of the hole, and the concentricity between the glass substrate and the hole are finely adjusted. (Inner / outer diameter precision processing step), the outer peripheral end surface and inner peripheral end surface of the glass substrate are polished to remove fine scratches (end surface polishing processing step). Next, both surfaces of the glass substrate are ground again, and the parallelism, flatness, and thickness of the glass substrate are finely adjusted (second lapping step). Then, both surfaces of the glass substrate are polished to make the surface unevenness uniform (polishing step). If necessary, both surfaces of the glass substrate are further polished using abrasives having different particle sizes (second polishing step). Finally, the glass substrate is cleaned and inspected and shipped as a glass substrate for a hard disk.
Japanese Patent Laying-Open No. 2003-63831 (stages (0002) to (0004), FIG. 6)

このように従来の方法では、例えば内・外周端面の加工に研削と研磨という２工程が必要であり、全体的に製造工程数が多く煩雑で製造効率が悪かった。また、ハードディスク基板を搭載する機器の小型・軽量化に伴って、ガラス基板の小径化が進みつつあるところ、小径のガラス基板を製造するには、例えば中央孔を空けるコアドリルを小径のものにしなければならない等、従来に比べ製造治具が小さくなるため作業が難しくなり、従来の同じ製造工程では製造効率が不可避的に低下する。   As described above, in the conventional method, for example, two steps of grinding and polishing are required for processing the inner and outer peripheral end faces, and the number of manufacturing steps is generally large and the manufacturing efficiency is poor. In addition, as the diameter of glass substrates is becoming smaller and smaller with the reduction in the size and weight of devices equipped with hard disk substrates, in order to manufacture small-diameter glass substrates, for example, a core drill that opens a central hole must be made small-diameter. For example, it is difficult to work because the manufacturing jig is smaller than the conventional one, and the manufacturing efficiency is inevitably lowered in the same conventional manufacturing process.

本発明はこのような従来の問題に鑑みてなされたものでり、その目的とするところは、中央孔を有し、内周端面および外周端面を面取り形状とした情報記録媒体用ガラス基板の製造方法において、製造工程数を少なくし、小径のガラス基板であっても高い効率で製造できるようにすることにある。   The present invention has been made in view of such conventional problems, and an object of the present invention is to manufacture a glass substrate for an information recording medium having a central hole and having a chamfered inner peripheral end surface and outer peripheral end surface. In the method, the number of manufacturing steps is reduced so that even a small-diameter glass substrate can be manufactured with high efficiency.

本発明者等は前記目的を達成するため鋭意検討を重ねた結果、金型成形による成形体の寸法精度は高く、また金型成形による成形体の表面性状は、研磨した場合のそれと同程度以上であるとの知見を得、プレス成形によって最終形状にできるだけ近い形状にするのがよいとの着想に基づき本発明をなすに至った。   As a result of intensive studies to achieve the above object, the present inventors have high dimensional accuracy of the molded body by mold molding, and the surface property of the molded body by mold molding is equal to or higher than that when polished. Based on the idea that the shape should be as close as possible to the final shape by press molding, the present invention has been made.

すなわち、本発明に係る情報記録媒体用ガラス基板の製造方法は、円柱状の穴の底面中央に円柱体が垂設された金型を用いて溶融ガラスをプレス成形して、中央に貫通孔が形成された円筒状成形体を成形する工程と、前記円筒状成形体を軸方向に対して垂直に切断して所定厚さのプリフォーム材に分割する工程と、前記プリフォーム材の外周端面および内周端面が接触する成形面が面取り形状とされた金型に、前記プリフォーム材を設置し、加熱成形する工程とを有することを特徴とする。
 That is, in the method for manufacturing a glass substrate for information recording media according to the present invention, a molten glass is press-molded using a mold having a cylindrical body suspended at the center of the bottom of a cylindrical hole, and a through-hole is formed at the center. A step of molding the formed cylindrical molded body, a step of cutting the cylindrical molded body perpendicularly to the axial direction and dividing it into a preform material having a predetermined thickness, an outer peripheral end surface of the preform material, and And a step of heat-molding the preform material in a mold having a chamfered molding surface with which the inner peripheral end surface comes into contact.

本発明に係る情報記録媒体用ガラス基板の製造方法では、従来は作製できなかった孔空きプリフォーム材を、円筒状成形体を薄く切断することによって作製し、このプリフォーム材をいわゆる再加熱法によって最終形状とするので、従来は必要であったラッピングやポリッシングなどの製造工程が不要となり、製造効率が大幅に向上できる。 In the method for producing a glass substrate for an information recording medium according to the present invention, a perforated preform material that could not be produced conventionally is produced by thinly cutting a cylindrical molded body, and this preform material is so-called reheating method. Therefore, the manufacturing process such as lapping and polishing, which has been necessary in the past, is unnecessary, and the manufacturing efficiency can be greatly improved.

以下、本発明に係るガラス基板の製造方法について図に基づいて説明するが、本発明はこれらの実施形態に何ら限定されるものではない。   Hereinafter, although the manufacturing method of the glass substrate which concerns on this invention is demonstrated based on figures, this invention is not limited to these embodiment at all.

図１は、第１の発明に係るガラス基板の製造方法の一例を示す工程図である。なお、従来の製造方法と比べて削除できる工程部分を破線で示している（図３においても同じ）。まず、ガラス素材を溶融する（ガラス溶融工程）。使用するガラス素材に特に限定はなく、リチウム・アルミノシリケート系ガラスやマグネシウム・アルミノシリケート系ガラス、ホウケイ酸系ガラスなどのガラス素材を、得ようとするガラス基板の所望の形態（結晶化ガラスまたは非晶質ガラス）に応じて適宜選択して用いればよい。   FIG. 1 is a process diagram showing an example of a method for producing a glass substrate according to the first invention. In addition, the process part which can be deleted compared with the conventional manufacturing method is shown with the broken line (same also in FIG. 3). First, a glass material is melted (glass melting step). The glass material to be used is not particularly limited, and a glass material such as lithium / aluminosilicate glass, magnesium / aluminosilicate glass, or borosilicate glass is obtained in a desired form (crystallized glass or non-crystallized glass). It may be selected and used as appropriate according to the crystalline glass.

次に、一定量の溶融ガラスを下型に滴下あるいは流し込み、溶融ガラスを上型で押圧してプレス成形する（プレス成形工程）。ここで図２に示すように下型２は、平板状の基部２１と、基部２１の上面に取り付けられた側部２２，２３と、側部２２，２３によって形成された貫通孔２５と同軸状に、基部２１の上面に垂設された円柱体２４とを備える。貫通孔２５の内周壁は、ガラス基板の外周端面の面取り形状に対応する成形面が軸方向に連続して形成されている。また側部を構成する右側部２２と左側部２３とはそれぞれ図の左右方向に移動可能である。   Next, a certain amount of molten glass is dropped or poured into the lower mold, and the molten glass is pressed by the upper mold to be press molded (press molding process). Here, as shown in FIG. 2, the lower mold 2 is coaxial with a flat plate-like base portion 21, side portions 22 and 23 attached to the upper surface of the base portion 21, and a through hole 25 formed by the side portions 22 and 23. And a cylindrical body 24 suspended from the upper surface of the base 21. On the inner peripheral wall of the through hole 25, a molding surface corresponding to the chamfered shape of the outer peripheral end surface of the glass substrate is formed continuously in the axial direction. Moreover, the right side part 22 and the left side part 23 which comprise a side part are respectively movable to the left-right direction of a figure.

図２（ａ）に示すように、貫通孔２５とその底部をなす基部２１とによって有底穴が形成され、この有底穴に溶融ガラス３が流し込まれる。そして、有底穴と嵌合し得る上型１によって押圧された後（同図（ｂ））、右側部２２と左側部２３とがそれぞれ左右方向に移動し、外周面に面取り形状が軸方向に連続し、中央に貫通孔４１が形成されたガラス基板前駆体４が取り出される（同図（ｃ））。   As shown in FIG. 2A, a bottomed hole is formed by the through hole 25 and the base portion 21 forming the bottom thereof, and the molten glass 3 is poured into the bottomed hole. Then, after being pressed by the upper mold 1 that can be fitted into the bottomed hole ((b) in the same figure), the right side portion 22 and the left side portion 23 move in the left-right direction, and the chamfered shape is axial in the outer peripheral surface. And a glass substrate precursor 4 having a through hole 41 formed in the center is taken out (FIG. 3C).

ここで、形成する面取り形状に特に限定はなく、ガラス基板の用途などから適宜決定すればよいが、面取り形状の傾斜面角度は一般に３０〜６０°の範囲が好ましく、その厚さ方向の幅はガラス基板の厚さに対して１／４〜１／３の範囲が好ましい。また、製造効率や成形性などの観点から、ガラス基板前駆体４の厚さはガラス基板を１０〜２０枚重ねた程度の厚さであるのが好ましい。そしてまた、プレス成形条件としては、従来の製造方法における成形条件と同様の成形条件を採用することができ、例えばプレス圧は２０〜１００ｋｇ／ｃｍ2、プレス時間は０．３〜２．０ｓｅｃの範囲が推奨される。 Here, the chamfered shape to be formed is not particularly limited, and may be appropriately determined from the use of the glass substrate, but the inclined surface angle of the chamfered shape is generally preferably in the range of 30 to 60 °, and the width in the thickness direction is The range of 1/4 to 1/3 is preferable with respect to the thickness of the glass substrate. In addition, from the viewpoint of manufacturing efficiency, moldability, and the like, the thickness of the glass substrate precursor 4 is preferably such that 10 to 20 glass substrates are stacked. As the press molding conditions, the same molding conditions as those in the conventional manufacturing method can be employed. For example, the press pressure is 20 to 100 kg / cm 2 , and the press time is 0.3 to 2.0 sec. A range is recommended.

そして次に、図１及び図２（ｄ）に示すように、プレス成形されたガラス基板前駆体４を結晶化処理またはアニール処理する。結晶化処理及びアニール処理のいずれを行うかは、得ようとするガラス基板の形態（結晶質または非晶質）に依存する。すなわち結晶性ガラス基板を得たい場合には結晶化処理を行い、非晶質ガラス基板を得たい場合にはアニール処理を行う。   Then, as shown in FIGS. 1 and 2D, the press-molded glass substrate precursor 4 is crystallized or annealed. Whether to perform crystallization treatment or annealing treatment depends on the form (crystalline or amorphous) of the glass substrate to be obtained. That is, when it is desired to obtain a crystalline glass substrate, a crystallization process is performed, and when it is desired to obtain an amorphous glass substrate, an annealing process is performed.

結晶化処理およびアニール処理の方法は、従来の製造方法における結晶化処理およびアニール処理の方法と同様の方法を用いることができる。例えば結晶化処理を行う場合には通常、（ガラス転移点Ｔｇ＋５０℃）〜（Ｔｇ＋３００℃）までガラス基板前駆体を加熱した後、一定温度を保持する、あるいは温度制御しながらＴｇ付近まで徐冷し、それ以降は放冷する。ここで加熱温度や保持時間、Ｔｇまでの冷却速度などを適宜選択することによって、熱膨張率やヤング率、結晶化度などのガラス基板の諸物性を調整できる。一方、アニール処理を行う場合には通常、Ｔｇ付近で一定時間保持後、歪点まで比較的遅い冷却速度で冷却し、その後比較的速い冷却速度で冷却する。   As the crystallization treatment and annealing treatment, the same method as the crystallization treatment and annealing treatment in the conventional manufacturing method can be used. For example, when a crystallization treatment is performed, the glass substrate precursor is usually heated from (glass transition point Tg + 50 ° C.) to (Tg + 300 ° C.) and then gradually cooled to near Tg while maintaining a constant temperature or controlling the temperature. After that, let cool. Here, various properties of the glass substrate such as a coefficient of thermal expansion, a Young's modulus, and a degree of crystallinity can be adjusted by appropriately selecting the heating temperature, the holding time, the cooling rate to Tg, and the like. On the other hand, in the case of performing an annealing treatment, usually, after holding for a certain time in the vicinity of Tg, the strain point is cooled at a relatively slow cooling rate, and then cooled at a relatively fast cooling rate.

次に、図２（ｅ）に示すように、ダイヤモンドカッタＣを用いてガラス基板前駆体４を所定厚さに切断してガラス基板５’とする。このガラス基板５’では、プレス成形によって中央孔５１が形成され、さらに外周端面５２が面取り形状とされているので、従来は必要であったコアリング工程、外径についての精密加工工程および端面研磨加工工程（いずれも図５に図示）を、本件発明の製造方法では省略することができ生産効率が格段に向上する。なお、切断するガラス基板５’の厚みは、ガラス基板の用途や後工程で切削・研磨をさらに行うかどうかなどを考慮して適宜決定すればよく、一般に０．１〜１．０ｍｍの範囲が好ましい。切断方法としてレーザ切断法やウォータジェット切断法などを用いてももちろん構わない。   Next, as shown in FIG. 2E, the glass substrate precursor 4 is cut into a predetermined thickness using a diamond cutter C to obtain a glass substrate 5 '. In this glass substrate 5 ′, the central hole 51 is formed by press molding, and the outer peripheral end face 52 is chamfered. Therefore, the coring process, the precision machining process for the outer diameter, and the end face polishing, which have been necessary in the past, are required. The processing steps (both shown in FIG. 5) can be omitted in the manufacturing method of the present invention, and the production efficiency is remarkably improved. In addition, the thickness of the glass substrate 5 ′ to be cut may be appropriately determined in consideration of the use of the glass substrate and whether or not cutting and polishing are further performed in a subsequent process, and generally ranges from 0.1 to 1.0 mm. preferable. Of course, a laser cutting method or a water jet cutting method may be used as the cutting method.

図１に戻って、ガラス基板前駆体４から切断・分離されたガラス基板５’に対して第１ラッピング処理が行われる。この第１ラッピング処理では、ガラス基板の両面が研磨されて所定の平行度、平坦度、厚みに予備調整される。ラッピング処理条件に特に限定はなく、従来公知の製造方法における処理条件をここでも採用できる。研磨材としては粒度が＃６００〜＃２０００の範囲、好ましくは＃８００〜＃２０００の範囲の固定砥粒（ダイヤペレット）や遊離砥粒（アルミナ、炭化ケイ素などのスラリー）を使用できる。またラッピング装置としては従来の公知の装置を使用でき、例えばハマイ社製やスピードファム社製の両面ラッピング装置が好適である。   Returning to FIG. 1, the first lapping process is performed on the glass substrate 5 ′ cut and separated from the glass substrate precursor 4. In the first lapping process, both surfaces of the glass substrate are polished and preliminarily adjusted to predetermined parallelism, flatness, and thickness. The lapping process conditions are not particularly limited, and the process conditions in a conventionally known manufacturing method can also be adopted here. As abrasives, fixed abrasive grains (diamond pellets) or loose abrasive grains (slurries such as alumina and silicon carbide) having a particle size in the range of # 600 to # 2000, preferably in the range of # 800 to # 2000 can be used. As the wrapping apparatus, a known conventional apparatus can be used. For example, a double-sided wrapping apparatus manufactured by Hamai or Speedfam is suitable.

ガラス基板の内周端面はプレス成形で形成された面であるが、面取り形状とされていないので、次にガラス基板の内周端面を研削して面取り形状とし、ガラス基板の中央孔の内径寸法、並びにガラス基板と孔との同心度を微調整した後（内径精密加工工程）、ガラス基板の内周端面を研磨して微細なキズ等を除去する（端面研磨加工工程）。研磨処理の方法は、従来公知のポリッシング処理の方法と同じ方法を用いることができる。例えば平均一次粒子径が２μｍ以下の酸化セリウムなどの研磨材を用いて、表面粗さ（Ｒａ）が１ｎｍ以下、好ましくは０．５ｎｍ以下、そして最大表面粗さ（Ｒｍａｘ）が２０ｎｍ以下、好ましくは１０ｎｍ以下まで本体部の切断面を研磨する。なお、表面粗さ（Ｒａ）及び最大表面粗さ（Ｒｍａｘ）はＪＩＳ Ｂ０６０１に基づく平均値及び最大値である。   The inner peripheral end surface of the glass substrate is a surface formed by press molding, but it is not chamfered, so the inner peripheral end surface of the glass substrate is then ground into a chamfered shape, and the inner diameter of the central hole in the glass substrate Then, after finely adjusting the concentricity between the glass substrate and the hole (inner diameter precision machining step), the inner peripheral end surface of the glass substrate is polished to remove fine scratches (end surface polishing processing step). As the polishing method, the same method as a conventionally known polishing method can be used. For example, using an abrasive such as cerium oxide having an average primary particle size of 2 μm or less, the surface roughness (Ra) is 1 nm or less, preferably 0.5 nm or less, and the maximum surface roughness (Rmax) is 20 nm or less, preferably The cut surface of the main body is polished to 10 nm or less. The surface roughness (Ra) and the maximum surface roughness (Rmax) are an average value and a maximum value based on JIS B0601.

次いで、ガラス基板の両表面を研削加工して表面の形状精度を修正する（第２ラッピング工程）。最終的なガラス基板としての形状品質（平行度、平坦度および厚み）を達成し、同時に後述のポリッシング工程で調整可能な表面粗さおよび最大表面粗さを達成する。この第２ラッピング処理における処理条件および使用装置は、前述の第１ラッピング処理で例示したものがここでも好適に採用および使用できる。   Next, both surfaces of the glass substrate are ground to correct the surface shape accuracy (second lapping step). Shape quality (parallelism, flatness, and thickness) as a final glass substrate is achieved, and at the same time, a surface roughness and a maximum surface roughness that can be adjusted by a polishing process described later are achieved. The processing conditions and the apparatus used in the second wrapping process can be suitably adopted and used here as exemplified in the first wrapping process.

第２ラッピング処理が終わると次にポリッシング処理が行われる。すなわち、ガラス基板の両表面を研磨加工して平滑性を調整する。ポリッシング処理の方法は従来公知の方法を採用することができ、例えば内周端面の前述の研磨処理で例示した方法および基準を適用できる。ポリッシング装置としては従来公知の装置を使用でき、例えば両面ポリッシュ盤（ハマイ社製）が挙げられる。   When the second wrapping process is finished, the polishing process is performed next. That is, the smoothness is adjusted by polishing both surfaces of the glass substrate. A conventionally known method can be adopted as the polishing method, and for example, the method and reference exemplified in the above-described polishing treatment of the inner peripheral end surface can be applied. As the polishing apparatus, a conventionally known apparatus can be used. For example, a double-sided polishing machine (made by Hamai Co., Ltd.) can be used.

最後に、ポリッシング処理されたガラス基板を洗浄し検査する。洗浄工程においてはガラス基板を常温の流水にさらすなどして基板表面に付着したガラスくずなどを除去する。検査工程では、ガラス基板の平行度、平坦度、厚み、表面粗さ、最大表面粗さ、同心度、真円度、端部形状（ロールオフ）、微小ウネリ等が所望の範囲内であるかどうかが検査され、製品としてのガラス基板とされる。   Finally, the polished glass substrate is cleaned and inspected. In the cleaning process, the glass substrate adhered to the substrate surface is removed by exposing the glass substrate to running water at room temperature. In the inspection process, whether the parallelism, flatness, thickness, surface roughness, maximum surface roughness, concentricity, roundness, end shape (roll-off), minute undulation, etc. of the glass substrate are within the desired range It is inspected and made into a glass substrate as a product.

次に、もう一つの発明に係る製造方法について説明する。この発明に係る製造方法の大きな特徴は、プレス成形によって作製した円筒状成形体を薄く切断して中央孔を有するプリフォーム材を作製し、このプリフォーム材をいわゆる再加熱法によって最終形態としてのガラス基板を作製することにある。   Next, a manufacturing method according to another invention will be described. A major feature of the manufacturing method according to the present invention is that a cylindrical shaped body produced by press molding is thinly cut to produce a preform material having a central hole, and this preform material is used as a final form by a so-called reheating method. It is to produce a glass substrate.

図３に、この発明に係る製造方法の一例を示す工程図を示す。なお、前述の製造方法と異なる工程を中心に以下説明する。ガラス素材を溶融した後（ガラス溶融工程）、溶融ガラスを成形用金型でプレス成形する。図４に示すように、この発明の製造方法ではプレス成形工程において、円柱状の穴６１の底面中央に円柱体６２が垂設された下型６に、一定量の溶融ガラス３を滴下あるいは流し込み（同図（ａ））、穴６１に嵌合し得る上型１で溶融ガラス３を押圧してプレス成形する（同図（ｂ））。これにより溶融ガラス３は、中央に貫通孔７１が形成された円筒状成形体７に成形される（同図（ｃ））。なお、製造効率や成形性などの観点から、円筒状成形体７の高さはガラス基板を１０〜２０枚重ねた程度の厚さであるのが好ましい。また、プレス成形条件としては、従来の製造方法における成形条件と同様の成形条件を採用することができ、例えばプレス圧は２０〜１００ｋｇ／ｃｍ2、プレス時間は０．３〜２．０ｓｅｃの範囲が推奨される。 FIG. 3 is a process chart showing an example of the manufacturing method according to the present invention. In addition, it demonstrates below centering on a process different from the above-mentioned manufacturing method. After melting the glass material (glass melting step), the molten glass is press-molded with a molding die. As shown in FIG. 4, in the manufacturing method of the present invention, in a press molding process, a certain amount of molten glass 3 is dropped or poured into a lower mold 6 in which a cylindrical body 62 is suspended from the center of the bottom surface of a cylindrical hole 61. (FIG. 5A), the molten glass 3 is pressed and press-molded with the upper mold 1 that can be fitted into the hole 61 (FIG. 5B). Thereby, the molten glass 3 is shape | molded by the cylindrical molded object 7 by which the through-hole 71 was formed in the center (the figure (c)). In addition, from the viewpoint of manufacturing efficiency, moldability, and the like, it is preferable that the height of the cylindrical molded body 7 is a thickness of 10 to 20 glass substrates stacked. Moreover, as press molding conditions, the molding conditions similar to the molding conditions in the conventional manufacturing method can be employed. For example, the press pressure is in the range of 20 to 100 kg / cm 2 , and the press time is in the range of 0.3 to 2.0 sec. Is recommended.

そして次に、図３及び図４（ｄ）に示すように、作製された円筒状成形体７を結晶化処理またはアニール処理する。結晶化処理及びアニール処理のいずれを行うかは、得ようとするガラス基板の形態（結晶質または非晶質）に依存する。すなわち結晶性ガラス基板を得たい場合には結晶化処理を行い、非晶質ガラス基板を得たい場合にはアニール処理を行う。結晶化処理およびアニール処理の具体的方法は、前述の方法がここでも例示される。   Then, as shown in FIGS. 3 and 4D, the produced cylindrical molded body 7 is subjected to crystallization treatment or annealing treatment. Whether to perform crystallization treatment or annealing treatment depends on the form (crystalline or amorphous) of the glass substrate to be obtained. That is, when it is desired to obtain a crystalline glass substrate, a crystallization process is performed, and when it is desired to obtain an amorphous glass substrate, an annealing process is performed. The specific method of the crystallization treatment and the annealing treatment is exemplified here as well.

次に、図４（ｅ）に示すように、ダイヤモンドカッタＣを用いて円筒状成形体７を所定厚さに切断してプリフォーム材８とする。これにより、従来は作製できていなかった、中央孔８１が形成されたプリフォーム材８を作製でき、後述する再加熱法により中央孔を有するガラス基板を作製できるようになる。なお、切断するプリフォーム材８の厚みは、製造するガラス基板の大きさや厚みなどを考慮して適宜決定すればよく、一般に０．１〜１．０ｍｍの範囲が好ましい。切断方法としてレーザ切断法やウォータジェット切断法などを用いてももちろん構わない。   Next, as shown in FIG. 4 (e), the cylindrical shaped body 7 is cut into a predetermined thickness using a diamond cutter C to obtain a preform material 8. Thereby, the preform material 8 in which the central hole 81 was formed, which could not be manufactured conventionally, can be manufactured, and a glass substrate having the central hole can be manufactured by the reheating method described later. In addition, the thickness of the preform material 8 to be cut may be appropriately determined in consideration of the size and thickness of the glass substrate to be manufactured, and is generally in the range of 0.1 to 1.0 mm. Of course, a laser cutting method or a water jet cutting method may be used as the cutting method.

そして、プリフォーム材８の内周端面および外周端面が接触する成形面が面取り形状とされている他、最終の製品形状に対応した成形面とされた金型９１，９２に、前記作製されたプリフォーム材８を設置する（同図（ｆ））。そしてプリフォーム材８を加熱して軟化状態にするとともに加圧して所定形状のガラス基板５を作製する（同図（ｇ）、（ｈ））。前述のように、金型による成形品は寸法精度が高く、またその表面性状は、研磨した場合のそれと同程度以上であるので、このようにして再加熱成形したガラス基板５は、その後洗浄するだけで直ちに製品となる。すなわち、従来は必要であった内外径精密加工や端面研磨加工、ラッピング、ポリッシングの各工程（いずれも図５に図示）が原則として不要となり、本発明の製造方法では製造効率が格段に向上するのである。もちろん、必要によりラッピング処理やポリッシング処理を行っても構わない。ラッピング処理およびポリッシング処理の具体的方法は、前述の方法がここでも同様に例示される。   In addition to the chamfered shape of the molding surface where the inner peripheral end surface and the outer peripheral end surface of the preform material 8 are in contact with each other, the molds 91 and 92 having the molding surfaces corresponding to the final product shape are manufactured as described above. The preform material 8 is installed ((f) in the figure). Then, the preform material 8 is heated to be softened and pressed to produce a glass substrate 5 having a predetermined shape (FIGS. (G) and (h)). As described above, the molded product by the mold has high dimensional accuracy, and the surface property thereof is equal to or higher than that when polished, and thus the glass substrate 5 reheated and molded in this way is then washed. Just become a product immediately. That is, the inner and outer diameter precision processing, end surface polishing processing, lapping and polishing steps (both shown in FIG. 5), which are conventionally required, are unnecessary in principle, and the manufacturing method of the present invention greatly improves manufacturing efficiency. It is. Of course, if necessary, a lapping process or a polishing process may be performed. The specific method of the lapping process and the polishing process is exemplified here as well.

本発明に係る製造方法の一例を示す工程図である。It is process drawing which shows an example of the manufacturing method which concerns on this invention. プレス成形の概説図である。It is a schematic diagram of press molding. もう一つの発明に係る製造方法の一例を示す工程図である。It is process drawing which shows an example of the manufacturing method which concerns on another invention. プレス成形及び再加熱成形の概説図である。It is a schematic diagram of press molding and reheating molding. 従来の製造方法を示す工程図である。It is process drawing which shows the conventional manufacturing method. 従来のプレス成形の概説図である。It is a schematic diagram of the conventional press molding.

符号の説明Explanation of symbols

１ 上型
２ 下型
３ 溶融ガラス
４ ガラス基板前駆体
５，５’ ガラス基板
６ 下型
７ 円筒状成形体
８ プリフォーム材
２１ 基部
２２ 右側部
２３ 左側部
２４ 円柱体
２５ 貫通孔
４１ 貫通孔
６１ 穴
６２ 円柱体
７１ 貫通孔
８１ 中央孔
９１ 上型
９２ 下型 DESCRIPTION OF SYMBOLS 1 Upper mold | type 2 Lower mold | type 3 Molten glass 4 Glass substrate precursor 5, 5 'Glass substrate 6 Lower mold | type 7 Cylindrical molded body 8 Preform material 21 Base 22 Right side 23 Left side 24 Cylindrical body 25 Through-hole 41 Through-hole 61 Hole 62 Cylindrical body 71 Through hole 81 Center hole 91 Upper mold 92 Lower mold

Claims (1)

中央孔を有し、内周端面および外周端面を面取り形状とした情報記録媒体用ガラス基板の製造方法であって、
円柱状の穴の底面中央に円柱体が垂設された金型を用いて溶融ガラスをプレス成形して、中央に貫通孔が形成された円筒状成形体を成形する工程と、前記円筒状成形体を軸方向に対して垂直に切断して所定厚さのプリフォーム材に分割する工程と、前記プリフォーム材の外周端面および内周端面が接触する成形面が面取り形状とされた金型に、前記プリフォーム材を設置し、加熱成形する工程とを有することを特徴とする情報記録媒体用ガラス基板の製造方法。 A method for producing a glass substrate for an information recording medium having a central hole and having a chamfered inner peripheral end surface and outer peripheral end surface,
A step of press-molding molten glass using a mold in which a cylindrical body is suspended at the center of the bottom surface of a cylindrical hole to form a cylindrical molded body having a through-hole formed in the center; and the cylindrical molding A step of cutting the body perpendicularly to the axial direction and dividing it into a preform material having a predetermined thickness; and a mold in which the outer peripheral end surface and the inner peripheral end surface of the preform material are chamfered A method of manufacturing a glass substrate for an information recording medium , comprising: a step of installing the preform material and performing heat molding .
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